The present invention relates to semiconductor devices in which a ferroelectric material or a high dielectric material is used for a capacitive insulating film, and methods for fabricating the devices.
Semiconductor devices in which a ferroelectric material or a high dielectric material is used for a capacitive insulating film have residual polarization that exhibits hysteresis characteristics, and a high dielectric constant. Such semiconductor devices therefore may replace semiconductor devices that have a capacitive insulating film made of silicon oxide or silicon nitride, in the field of nonvolatile memory devices and DRAM devices.
However, ferroelectric materials and high dielectric materials, which are oxides whose crystal structure determines the physical characteristics thereof, are affected greatly by hydrogen reduction. Nevertheless, MOS-transistor formation process, multilevel-interconnect formation process, and passivation-film formation process, for example, include many process steps in which not only hydrogen gas but also, for example, silane gas, resist material, and water (moisture) that contain hydrogen atoms are used.
In view of this, technology has recently been proposed in which a hydrogen-barrier layer is provided to the lateral portion of the capacitors, covering each capacitor element itself, or with pluralities of the capacitors as units, the entireties.